Fresh Rebuild - Knocking Noise

[Anonymous]

I have a freshly rebuilt 200. Just fired it up a couple of weeks ago for the first time. Since the first time it fired the engine has had this knocking noise that I have failed to diagnose. I have timed the engine and tuned the carb (as best I could with the car just idling) and it runs fine, starts right up but has this terrible knocking noise. I used a steathascope and the noise seems strongest under the oild pan at the back of the engine near the tranny. The noise speeds up and slows down with the engine RPM.

Does anyone have any idea what the noise may be?????

 

[rbohm]

8) a couple of possibilities;
1: bad main bearing
2: bad rod bearing
3: converter low on fluid(assuming an automatic)

check #3 first.

 

[Anonymous]

Loose bolt on the flexplate.

 

[Anonymous]

Do you have the roller tipped rockers??

Doug

 

[falcon fanatic]

I think I would drop the pan and have a look before I did any more running of that engine. If the problem is bearing related the wallet you save may be your own.

 

[Anonymous]

rbohm, i do have an automatic and my question to you is can a torque converter low on fluid really make a knocking noise? If so I assume the only way to fill it is to take it out.

I'm going to see if I can't get the engine builder to come by my house and listen to the noise.

Geezer, no I don't. That is a planned upgrade but not there yet. Here is a little history for you. The push rods that came with my isky cam kit are for adjustable rockers. The engine has non-adjustable rockers so the engine builder had to use the stock push rods. I have a spare rocker assembly but didn't realize until after the build was done that it was an adjustable set. At any rate since it was already built, I decided to run the engine as it was. When I fired it up and heard the noise i tried a few simple things first but most recently (yesterday) I installed the adjustable rockers with the isky chromoly push rods and valve stem caps. Adjusted the valves and fired it up to no avail. Engine still ran fine but noise hasn't changed.

So that is where I'm at now. Just a real frustrating experience as I have waited so long to drive my car and now this.

Anyway, life goes on. Thanks to all for the prompt responses.

 

[CobraSix]

Check for exhaust leaks...and also check your oil pan, my oil pan was bent up and my #6 counterweight was hitting the oil pan. Very loud.

Slade

 

[Anonymous]

Check to make sure the thrust bearing is on the #5 cap also. Otherwise, your crank could be walking causing the torque coverter to be hitting the starter.

 

[ksugita]

I had noise like that before.
It turned out that the back side of oil pan was indented and crank was hitting on the spot.
All I did was remove oil pan, and hummered out the indent.
I hope yours is the same problem. quick fix

good luck
Katsuo

 

[Anonymous]

For what it's worth:

I had the same situation happen to me when I first started up my rebuild. The knocking drove me nuts! I took down the oil pan and could not find anything wrong. Although every time I rotated the crank around, I could feel some resitance at the same point in the rotation. I ended up pulling the tranny from the engine and rotated the crank only to determine that it was in the tranny. I found that the balancing weight on the newly rebuilt torque converter was scrapping the inside of the bell housing. I ground down the inside of the bell housing and that was it. What a hassle for such a little thing!!

 

[Lazy JW]

I have seen a crank that had one rod journal ground smaller than the others. I have also seen one rod bearing out of a set that was bigger than the rest. Now I plastigauge EVERY one of them. It takes longer, but I know what I have.
Joe

 

[rbohm]

rbohm, i do have an automatic and my question to you is can a torque converter low on fluid really make a knocking noise? If so I assume the only way to fill it is to take it out.

8) actually you just need to check the fluid level in your tranny. and yes a converter that is low on fluid can cause said knocking. in fact it was found by one of my college instructors that some ford automatics, the C4 in particular will do just that.

 

[Anonymous]

will it knock in a manual tranny?

my tranny sliiping has gone away. i think it might have been leaky on discs.....bringing me to that first question
chaz

 

[falcon kyle]

The noise on my rebuild went away when my daughter threw #5 threw the oil pan. Either i forgot to torque a bolt or it just decided to brake either way i got to rebuild it again. No noise this time. And i hope this does not happen to you are anybody else.

 

[Anonymous]

Well I fired it up again yesterday afternoon to test the noise when the car drops into gear. The noise persisted. I then felt the oil pan with my hand. You could barely feel the vibration in the front of the oil pain but it was extermely evident in the back of the pan. If it is a bearing or something of the sort it's under the number #6 cylinder.

At any rate I talked to my builder and he is going to come by and take a listen. I have a feeling that either the pan is about to be dropped or the tranny disconnected. Those are the only logical steps left to take. If it was a lifter I can't imagine you would feel the vibration at the bottom of the oil pan.

Thanks again for everyone's input and I will let you know what the outcome is.

 

[wsa111]

sir, pull 1 spark plug wire one at a time and see if you can pinpoint which cylinder is the noise maker. also check the converter bolts are not hittting the starter nose??? good luck william

 

[Anonymous]

Already tried both of those suggestions to no avail.

 

[Anonymous]

So the engine builder came buy Saturday to listen to the noise my engine is making. He noticed a small indentation on the back of the oil pan where the noise is most noticable. Right above the tierod. It's possible I hit that dropping it in. He doesn't think it's anything serious in the engine. He brought over an Oil pressure gauge and it was running 40 at idle.

At any rate i started dropping the pan yesterday. Just need to remove the engine crossmember (it's being real stubborn) or lift the engine about an inch to clear the balancer.

With the sway bar out of the way and the oil pan just about out I'm thinking about replacing both with the 6qt pan and built in windage tray and a perormance sway bar!! LOL First, I need to verify the noise before I go spend anymore money!

I'll repost once it's off and verify the noise is something hitting the pan as we suspect.

 

[Anonymous]

Well I got the pan dropped and damn if that wasn't the problem. Right where that dent is there are some serious scraping marks. Well, glad that is all it was.

If anyone wants a slick way to drop the pan without taking down the crossmember I've got one for you.

Even with a impact gun at 80PSI the cross member bolts wouldn't move an inch. So i started to think. I put the oil pan back on with just a couple of bolts, loosened up the tranny crossmember so the tranny would pivot with the engine. Put a floorjack under the engine and unbolted the engine mounts. Then jacked up the engine so the bottom hole in the block lined up with the top hole on the engine mount and snugged up the engine mounts. At this point you have enough clearance to drop the pan with the cross member in place as the engine is sitting about an inch higher the before. Worked like a charm.